The natural teeth are often lost as a result of dental disease, trauma or injury. In recent years, more and more dentists and oral surgeons have turned to dental implants as an acceptable and appropriate means to restore a tooth that has been lost because of disease or trauma. Such dental implants offer an attractive alternative to other options because with a dental implant the patient realizes a restoration that closely approximates a natural tooth without having to alter the structure or appearance of adjacent natural teeth which occurs, for example, when a patient chooses a bridge option.
Typically in conventional processes, an implant operation begins with the extraction of the tooth. After extraction, the patient is sent home for a period of time, approximately 3 to 12 months, during which time the extraction or root cavity formed by the extraction is allowed to close and heal. This is because, typically, commercial implants are of a cylindrical shape and consequently do not naturally fit the general taper or conical shape of the extraction cavity. Consequently, conventional cylindrical shaped implants cannot be inserted directly into the natural tapered extraction cavity. Therefore, after extraction, the extraction cavity must be allowed to be close through healing. After the root cavity has closed and healed, the patient returns for further procedures. Here, the healed site is drilled to form an implant cavity in the area formally occupied by the extracted tooth. The size of the bore or cavity formed by the drill is slightly less than the diameter of the particular implant selected. Once the implant cavity has been formed, the implant is either inserted into the cavity with friction grip or screwed into the cavity with self-tapping threads. Thereafter, a second healing period follows. Time is required for the bone tissue surrounding the implant to grow up against and mechanically lock the implant in place. Typically, depending on the age of the patient and the site in the mouth, the second healing period can extend for approximately 3 to 12 months. Once integration has been reached, that is where the bony tissue fully grows in direct apposition to the implant, the dentist can install a false teeth or prosthesis onto the implant.
While dental implants are generally desirable, it is obvious that they come with some problems and much inconvenience. It is not uncommon for the period between tooth extraction and the final fitting of the prosthesis to be 6 to 18 months. Moreover, during that extended period, the patient may have to tolerate inconvenience, discomfort and sometimes pain.
Besides the time and inconvenience associated with conventional procedures for implanting, it is also difficult in some cases to properly orient the implant and maintain it stable after the prosthesis has been fitted. Obviously, insertion-type implants may tend to lack substantial implant-bony tissue contact from the outset. This can contribute to longer healing periods. Because of the lack of substantial close bone contact, it can take prolonged periods of time before the implant and the bony tissue integrate. Screw-type implants also are difficult to orient and stabilize. Typically, the thread pattern of screw-type implants require multi turns to set the implant. The hardness of the bony tissue in and around the implant cavity varies. With a multi turn implant, the threads tend to draw the implant towards and through softer bony tissue. This can results in the entire implant misaligning within the alveolar bone structure of the patient.
Finally, implants are typically designed such that they conform to a generally cylindrical configuration. In addition, typical implants are of a single piece construction and do not include additional or auxiliary means for interlocking the implant to the alveolar bone structure. Once the prosthesis has been attached to the top portion of the implant and the patient starts to use the implant to chew food, the stress, vertical and lateral forces, and rotational torques placed on the prosthesis are transferred downwardly to the implant. In cases where the implant is not stable and tightly secured within the implant cavity, the implant tends to rotate and turn under these stresses, forces and torque. This results in the implant becoming loose within the implant cavity and that often results in the implant becoming dislodged from the cavity or being so loose and unstable within the cavity that the same has to be removed from the patient's alveolar bone.
Finally, as noted above, most typical implants that are commercially available today include a cylindrical configuration. Thus, the outer walls are not generally tapered or conical. This cylindrical configuration results in substantial stresses and forces being concentrated at the lower end of the implant and those concentrated stresses and forces tend to loosen the implant and make the implant unstable within the patient's mouth.